We usually get 30L sacks of wood-based cat litter for our two rabbits' litter trays. It's a brand I've used for well over a decade and used to pay around £8, but up to £12 in the last 18 ish months. We got it on Amazon and have Prime and one sacks lasts about 5 weeks so we didn't mind paying a little extra for better quality litter delivered to our door.
Yesterday we realised we'd almost run out, so I went straight to Amazon to order. It's just under £18 now, for the same sized bag.
We ended up going to Pets at Home and buying two 30L bags at £7.99 each (plus the cost of fuel). The quality is terrible but we're having to make some sacrifices here and there.